With the current increased awareness for the need for proper diet and physical exercise, new exercise equipment is being developed and advances are being made in existing equipment, including in exercise rowing machines. Modern exercise rowing machines provide a substantially complete workout; they may be used to exercise not only the muscles of the arms and legs, but also the muscles of the shoulders, lower back and stomach.
In general form, exercise rowing machines typically include a frame, a seat adapted to slide or roll along the frame for supporting the rower, and foot pedals for receiving and anchoring the feet of the rower. The rowing machine also includes a manually graspable handle, oars or similar members, which are pulled or pivoted toward the rower during the pull stroke while the rower simultaneously pushes against the foot pedals to straighten his legs, thereby causing the seat to roll or slide rearwardly along the frame. Various types of mechanical or hydraulic resistance mechanisms are employed for resisting the pull on the handle or oars by the rower. During the return stroke, the pull on the handle or oars is relaxed while the legs are simultaneously bent to allow the seat to roll or slide forwardly along the frame.
In one particular type of exercising rowing machine, as disclosed in Swedish Pat. No. 78,675, the seat is mounted on rollers that ride in tracks extending along opposite sides of an elongated frame. The tracks are constructed in the form of upwardly open channels. A transverse handle is gripped by the rower for pulling against a resistance mechanism in the form of an extension spring located beneath the frame. A cable interconnects one end of the spring with the handle and a pulley is mounted on the forward end of the frame around which the cable extends. During the pull stroke the rower simultaneously pushes against foot pedals to straighten his legs, thereby causing the seat to roll rearwardly, and pulls on the handle to extend the extension spring. During the return stroke the pull on the handle is relaxed while the legs are simultaneously bent to permit the seat to roll forwardly along the frame.
A somewhat similar type of rowing machine is disclosed by U.S. Pat. No. 4,284,272, with the exception that the handle is mounted on the upper end of a post to form a "T-handle", and the lower end of the post is pivotally mounted on the forward end of the frame. A resistance load is applied to the T-handle by a clock-type spring, rather than an extension spring. Also, the seat is mounted on rollers that ride over the exposed outer surface of a pair of spacedapart, longitudinal tubes that compose the frame. The rear end of the frame is supported above the floor by a crank-shaped, tubular support structure that may be rotated between an extended position supporting the frame off the ground and a retracted position wherein the rear end of the frame is resting on the ground for more compact storage of the machine when the machine is not in use.
In another type of exercise rowing machine, the lower ends of a pair of manually graspable oars are pivotally mounted on the machine frame. Hydraulic shock absorbers are pivotally connected between the forward end portions of the frame and intermediate locations along the length of the oars. During use, as the legs of the rower are being extended, the oars are stroked in a manner similar to the of a scull. A valve is integrated into the piston of the hydraulic shock absorber to allow metered flow of hydraulic fluid from one side of the piston to the other during stroking of the oars. Examples of this type of exercise rowing machine are disclosed in: U.S. Pat. Nos. D268,194; D268,278; and, UK Patent No. 2,120,560, and also is marketed by West Bend Company of West Bend, Wisconsin under the model designation "5200." In the '194 and '278 U.S. Patents, the seat is mounted on a carriage having rollers that ride on tracks in the form of a pair of parallel, spaced apart tubes extending '560 longitudinally of the frame. The outer surface of the rollers are concave to match the diameter of the tubes. In the West Bend Model 5200 rowing machine, the seat is supported by rollers that ride within tracks that are formed in the sides of the longitudinal center beam of the machine frame. The tracks are open in the laterally outward direction.
A common drawback of the above-discussed rowing machines is that the tracks on which the seat rollers ride are exposed and, thus, can be damaged by rough usage or by objects falling onto or otherwise hitting the tracks. Also, in the types of rowing machines having channel-type tracks, objects can be lodged in the channels, thereby preventing free movement of the rollers and possibly causing damage to the rollers. Also in many of the types of rowing machines discussed above, the level of resistance on the handle or oars can be selectively adjusted; however, the load on the legs of the rower is not adjustable, other than by virtue of the resistance on the handle or oars.